1. Field of the Invention
The present invention relates to a suction-holding device which is attached by suction to the surfaces of various objects and used to move these objects, etc.
2. Prior Art
In the past, suction-holding devices have been widely used in order to move pieces of glass and large tiles, etc. that have flat suffices. Suction-holding devices of this series that have been proposed include: a die-cast base disk body having a rim downwardly protruding from the outer circumference of its undersurface face so as to form a hollow cavity section that opens in the downward direction; a suction disk disposed beneath the base disk body so as to cover the hollow cavity section, the suction disk being made of a rubber material and having a slightly larger diameter than the base disk body; an operating rod provided vertically on an embedded plate that is embedded in the top portion of the suction disk; and an operating handle which is disposed on the base disk body so as to pivot up and down and to which the operating rod protruded on the base disk body is connected.
In this suction-holding device, suction-holding of the suction disk to the surface of an object is accomplished by raising the operating handle upward, and the release of the suction-holding of the suction disk from the surface of the object is accomplished by pushing the operating handle down. Since a strong suction-holding force is obtained by causing the suction-holding of the suction disk to the surface of the object, such a suction-holding device is widely used in work in which the suction-holding device is used to lift and move the object.
As shown in FIG. 4(a), in order to stabilize the suction-holding state of the suction disk with respect to the surface of the object, an annular projection 6a in which a sharp rim 6b is formed by joining an outside inclined suffice and an inside vertical surface is formed as an integral unit with the suction disk 6 on the outer circumferential portion of the suction-holding surface of the suction disk 6. During use, the suction-holding to the surface of the object pushes the annular projection 6a against the surface of the object. When the operating handle is raised upward in this state so that the top portion of the suction disk is forcefully lifted via the operating rod, the space inside the suction disk surrounded by the annular projection 6a is placed in a vacuum state, and the annular projection 6a is deformed into a shape in which this projection is bent inward around the entire circumference (i.e., a shape in which the sharp rim 6b is pulled inward). As a result, the outside inclined surface forming the annular projection 6a adheres tightly to the surface of the object and is stabilized around the entire circumference as shown in FIG. 4(b).
When the suction-holding device that has a suction disk on which an annular projection is formed as described above is used, considering the state in which the annular projection adheres tightly to the surface of the object, the annular projection is deformed into a shape that is bent inward around the entire circumference as the degree of vacuum in the space inside the suction disk surrounded by the annular projection increases. Accordingly, the outside inclined surface that forms the annular projection contacts the surface of the object with the sharp rim on the inside, and the inclined surface adopts a width that is proportional to the degree of vacuum inside the suction disk, so that this inclined surface adheres tightly to the surface of the object in this range.
However, in the case of a suction disk in which the inclined surface that forms the annular projection is caused to adhere tightly to the surface of the object as described above, in order to prevent outside air from invading the interior of the suction disk, not only are there limits to the width of the inclined surface of the annular projection that is caused to adhere tightly to the surface of the object, but the objects that can be handled are also limited to objects that have a smooth surface. In other words, objects that are suctioned and moved, etc. using such a suction-holding device that has a suction disk on which an annular projection is formed are limited to pieces of glass and tiles, etc. that have flat surfaces.